JPH0330578Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a flexible exhaust pipe that flexibly connects exhaust pipes to each other in an exhaust system of an internal combustion engine or the like.

[Conventional technology]

In the exhaust system of an internal combustion engine, a flexible exhaust pipe is used that connects the exhaust pipes using a flexible bellows pipe in order to prevent vibrations or excessive displacement of the internal combustion engine from being transmitted to the exhaust pipe. There is. In a flexible exhaust pipe using a bellows pipe, the bellows pipe has a corrugated shape, so the exhaust gas flow passing through the bellows pipe may generate wind noise, and the bellows pipe may resonate due to the pulsating pressure of the exhaust gas. Noise is generated.

In order to prevent this wind noise or noise, an exhaust gas pipe is inserted into the bellows pipe so that the exhaust gas flow or the pulsating pressure of the exhaust gas does not directly hit the bellows pipe. (For example, Utsukai 55-
110723, Japanese Utility Model Publication No. 110723, No. 110-87330) [Problem to be solved by the invention] However, in the conventional flexible exhaust pipe in which the exhaust gas pipe is inserted into the bellows pipe, the gap between the inner wall surface of the bellows pipe and the exhaust gas pipe is small. Because of the small amount of displacement, the bellows pipe and the exhaust gas pipe interfere with each other in response to large displacements, causing abnormal noise and deteriorating flexibility, resulting in the problem that excessive displacements of the internal combustion engine cannot be absorbed. In order to increase the gap between the inner wall surface of the bellows pipe and the exhaust gas pipe, reducing the inner diameter of the exhaust gas pipe increases ventilation resistance.
Furthermore, when the outer diameter of the bellows tube is increased, a problem arises in that the flexibility of the bellows tube deteriorates.

The present invention solves the above-mentioned problems of the conventional technology.In a flexible exhaust pipe in which an exhaust gas pipe is inserted into a bellows pipe, the present invention solves an increase in the ventilation resistance of exhaust gas and a deterioration in the flexibility of the bellows pipe. The purpose is to prevent the bellows pipe and the exhaust gas pipe from coming into contact with each other due to large displacement without causing any damage.

[Means to solve the problem]

In order to achieve this objective, the following measures are taken in the present invention.

That is, in a flexible exhaust pipe comprising a bellows pipe having an exhaust gas inlet and an exhaust gas outlet, and an exhaust gas pipe disposed inside the bellows pipe to prevent exhaust gas from hitting the inner wall surface of the bellows pipe, the bellows The pipe has a structure in which the inner diameter increases from a small diameter part located in the axial center to large diameter parts located at both ends, and the exhaust gas pipe is fixed to the small diameter part of the bellows pipe, and the large diameter part at both ends increases. The inner diameter of the exhaust pipe is approximately equal to the inner diameter of the exhaust gas inlet of the bellows pipe.

[Effect]

Since the exhaust gas pipe of the present invention is fixed to the bellows pipe at the center of the bellows pipe, even if the bellows pipe bends significantly, the exhaust gas pipe can be displaced in the direction of the bending of the bellows pipe, and both ends of the exhaust gas pipe exists in the large diameter portions formed at both ends of the bellows pipe, so both ends of the exhaust gas pipe do not come into contact with the bellows pipe. Therefore, the exhaust gas pipe never comes into contact with the bellows pipe.

In addition, since the exhaust gas pipe extends to both ends of the bellows pipe, this exhaust gas pipe alone can prevent the exhaust gas flow from directly hitting the bellows pipe, and it is not necessary to insert other exhaust pipes into the bellows pipe. Since this is not necessary, interference between the bellows pipe and other exhaust pipes does not occur.

Furthermore, since the inner diameter of the exhaust gas pipe and the inner diameter of the exhaust gas inlet are approximately equal, no increase in ventilation resistance occurs.

Note that since the bellows tube has a large inner diameter at both ends but a small inner diameter at the center, the flexibility of the bellows tube itself will not deteriorate.

The effect of the present invention will be made clearer from the following examples.

〔Example〕

FIG. 5 is a side view of the entire exhaust system including the flexible exhaust pipe 10.
0 is provided in the middle of the exhaust pipe 1. In Fig. 5, 2 is the engine, 3 is the exhaust manifold, and 4 is the engine.
is a catalytic converter, and 5 is a muffler. Also, 6
is a suspension member that suspends the entire exhaust system from the vehicle body.

FIG. 1 is a longitudinal sectional view of a flexible exhaust pipe according to an embodiment of the present invention.

In FIG. 1, the flexible exhaust pipe 10 is
It includes a bellows pipe 11 and a wire mesh knitted pipe 12 for protecting the bellows pipe 11 from flying stones and the like. The flexible exhaust pipe 10 has a structure in which a bellows pipe 11 is wrapped in a wire mesh knitted pipe 12. 21 is an exhaust gas inlet, and 22 is an exhaust gas outlet. Arrow G represents the flow of exhaust gas.

At the exhaust gas inlet 21, the bellows pipe 11 and the wire mesh knitted pipe 12 are welded together with a metal band 23. The exhaust pipe 1 (see FIG. 5) is inserted into the exhaust gas inlet 21.

Also at the exhaust gas outlet 22, the bellows pipe 11 and the wire mesh knitted pipe 12 are welded together with the metal band 24. The exhaust pipe 1 (see FIG. 5) is also inserted into the exhaust gas outlet 22.

In this embodiment, an exhaust gas pipe 13 is disposed inside the bellows pipe 11. The inner diameter of the exhaust gas pipe 13 is approximately equal to the inner diameter of the exhaust gas inlet 21 and the inner diameter of the exhaust gas outlet 22. The exhaust gas pipe 13 is made of metal pipe.

The inside diameter of the bellows tube 11 is made small at the central portion in the axial direction, and increases toward the large diameter portions located at both ends.

The exhaust gas pipe 13 is welded to the bellows tube 11 at a small diameter portion located in the center of the bellows tube 11, and the exhaust gas pipe 13 is free and is not supported anywhere other than this portion. and,
The exhaust gas pipe 13 extends to large-diameter portions located at both ends of the bellows tube 11 , and the exhaust gas pipe 13 exists over substantially the entire axial direction of the bellows tube 11 .

The welding structure of the exhaust gas pipe 13 to the bellows pipe 11 will be explained.

FIG. 2 is an enlarged side view of the central portion of the bellows tube 11 of FIG. 1. As can be seen from FIG. 2, a parallel portion 31 is provided in the axially central portion of the bellows tube 11. The parallel part 31 has an exhaust gas pipe 1
3 has been inserted. Further, a large number of holes 32 are bored in the parallel portion 31.

The outer surface of the exhaust gas pipe 13 is visible through the hole 32. At the hole 32, as shown in FIG. 3 (FIG. 3 is an enlarged cross-sectional view of FIG. 2)
As shown in FIG. 2, the exhaust gas pipe 13 and the bellows pipe 11 are fixed together by welding overlay 33.

The operation of this embodiment will be explained.

Since the exhaust gas pipe 13 is welded to the bellows pipe 11 at the center of the bellows pipe 11,
Even if the exhaust gas pipe 13 is bent, the exhaust gas pipe 13 can be displaced in the direction of the bending together with the bellows pipe 11, and
Since both ends of the exhaust gas pipe 13 are located at the large diameter portions of both ends of the bellows pipe 11, it is also possible to prevent both ends of the exhaust gas pipe 13 from coming into contact with the inner wall of the bellows pipe 11. Therefore, even if the bellows pipe 11 is bent, the condition shown in FIG. As shown in FIG. 1), the exhaust gas pipe 13 can be displaced together with the bellows pipe 11 without coming into contact with the bellows pipe 11.

Since the exhaust gas pipe 13 is present over substantially the entire axial direction of the bellows pipe 11, the exhaust gas flow can be prevented from directly hitting the bellows pipe 11 only by the exhaust gas pipe 13. Therefore, the exhaust gas inlet 22 or the exhaust gas outlet 2
Since there is no need to insert other exhaust pipes etc. into the bellows pipe 11 from 2, interference between other exhaust pipes etc. and the bellows pipe 11 does not occur.

Further, the inner diameter of the exhaust gas pipe 13 is made substantially equal to the inner diameter of the exhaust gas inlet 21 and the inner diameter of the exhaust gas outlet 22, so that the ventilation resistance of the exhaust gas does not increase.

Furthermore, since the bellows tube 11 of this embodiment has a large inner diameter at both ends but a small inner diameter at the center, the flexibility of the bellows tube 11 will not deteriorate.

In this embodiment, the bellows tube 11 has a special shape as shown in FIG. 1, but such molding is easy and this itself hardly causes an increase in cost.

〔effect〕

According to the present invention, the inside diameter of the bellows pipe is expanded from the small diameter part located at the center in the axial direction toward the large diameter parts located at both ends, and the exhaust gas pipe is fixed to the small diameter part of the bellows pipe. Since the exhaust pipe extends to the large diameter portions at both ends, and the inside diameter of the exhaust pipe and the inside diameter of the exhaust gas inlet of the bellows pipe are made approximately equal, the ventilation resistance of the exhaust gas increases and the flexibility of the bellows pipe deteriorates. This has the effect of preventing the bellows pipe from coming into contact with the exhaust gas pipe due to large displacement.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view of a flexible exhaust pipe according to an embodiment of the present invention, FIG. 2 is an enlarged side view of the middle part of the flexible exhaust pipe of FIG. 1, and FIG. 3 is a side view of the flexible exhaust pipe of FIG. - An enlarged cross-sectional view; FIG. 4 is an explanatory diagram illustrating a bent state of the flexible exhaust pipe of FIG. 1; and FIG. 5 is a side view of the entire exhaust system including the flexible exhaust pipe. 10... Flexible exhaust pipe, 11... Bellows pipe, 13... Exhaust gas pipe, 21... Exhaust gas inlet, 22... Exhaust gas outlet.

Claims (1)

[Claims for Utility Model Registration] A flexible device comprising a bellows pipe having an exhaust gas inlet and an exhaust gas outlet, and an exhaust gas pipe disposed inside the bellows pipe to prevent exhaust gas from hitting the inner wall surface of the bellows pipe. In the exhaust pipe, the inside diameter of the bellows pipe increases from a small diameter part located at the center in the axial direction toward large diameter parts located at both ends, and the exhaust gas pipe is fixed to the small diameter part of the bellows pipe. The flexible exhaust pipe is extended to large diameter portions at both ends, and the inner diameter of the exhaust pipe is substantially equal to the inner diameter of the exhaust gas inlet of the bellows pipe.